Water pump failure at 140,000 miles, replaced it myself for$50.00 for parts, $28.00 for a special wrench to remove and replace the pump available at O'Reillys autoparts and information from internet.
EGR Valve and intake manifold need to clean, will do it myself, (I am not a mechanic, I just learned to fix my own cars by using commonsense)
Transmission speed sensor needs replacement but it can be fixed by any do it yourselfer. Not a big deal.
I bought this car for my wife mainly because of its gorgeous looks, it looked very majestic with all the hood ornament and Cadillac emblems all over the car and it gleaminG metallic garnet red color. Little did we realize what pleasant surprises we were headed for. This car gave 26-28 MPG on highway at speeds of 70-80. I noticed initially that it used almost 1 quart of oil every 800 miles or so which is considered normal for this car, I realized this problem was largely eliminated on changing over to Valvoline 10W30 High Mileage oil while also improving compression noticeably. This car has received many compliments about its appearance in-spite of its age. With it 300 Horse power North-star motor it has surprisingly great acceleration for a big sized sedan along with a silken ride. The load levelling suspension is very dependable. For $6000 and over 26.000 "worthwhile" miles besides having preserved its aristocratic looks, I have recovered every dime's worth of this car. Every mile hereon is a bonus. I highly recommend the STS of this vintage to any American young or elderly couple looking for a mid-sized luxury sedan because of their dependability, reliability, scores of features (both technical and non technical) and ridiculously low prices compared to the imported counterparts. I will love to keep this car as long as it maintains it appearance. My previous car, a 1986 Lincoln Town Car, (still own it because of its classic appeal and mint condition) although equally my favorite cannot be compared with the STS, its like comparing a rear wheel drive luxury land yacht with a front wheel drive luxury sedan. The 225R16 60 tires are a wonderful match for this car, for exceptional handling in the rain, I wouldn't recommend hard cornering at high speeds on wet surfaces although I have never experienced any problem so far. At nearly 150 K almost everything electrical on this car works perfectly and the climate control mechanisms performs great, except for a louder hum from the blower fan motor when the rear passenger seating area climate control is turned all the way to the maximum. Iguess that's not bad for this age and miles. I want to own the 2 door ElDorado with the same motor and transmission mechanisms for the sporty look and elegant trunk design
Consider yourself extremely fortunate. I had a 1997 SLS which I loved, but had to give it away (for a much lower price than when I purchased it) due to constant, expensive repairs. I have said it before, I literally maxed out a credit card getting the Caddy fixed over and over again. I said I will never drive an American car again, much less Cadillac. however, if the new DTS proves itself worthy of the crest, then I might get a used one down the road, along with an extended warranty.
Some people complain for no reason on repairing the STS Cadillac. Hey people, it is normal, like every other used car to replace the alternator, ball joints, water pump, after 100,000 plus miles. To any expensive or import cars, these problem are normal, those parts don't last forever.
I myself owned a 1994 SLS, later bought a 1988 Town car and currently drive a 98 mark viii. I can't decide which I love the most.